There really can't be ONE king of the 303 in my opinion, because looking back at my record collection, a majority of the really good acid techno classics are a collaberative effort. But the people who stand out the most when it comes to making some killer acid lines would have to be: DDR, D.A.V.E. the Drummer, Rowland the Bastard, Chris Liberator and Lawrie Immersion.